1656640 has 56 divisors (see below), whose sum is σ = 4096512. Its totient is φ = 637440.

The previous prime is 1656631. The next prime is 1656647. The reversal of 1656640 is 466561.

It is a junction number, because it is equal to n+sod(n) for n = 1656599 and 1656608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1656647) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9837 + ... + 10003.

It is an arithmetic number, because the mean of its divisors is an integer number (73152).

2^1656640 is an apocalyptic number.

1656640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1656640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2048256).

1656640 is an abundant number, since it is smaller than the sum of its proper divisors (2439872).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1656640 is a wasteful number, since it uses less digits than its factorization.

1656640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 215 (or 205 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 1656640 is about 1287.1052792992. The cubic root of 1656640 is about 118.3248732077.

The spelling of 1656640 in words is "one million, six hundred fifty-six thousand, six hundred forty".